Closed hydraulic oil cylinder system driven by motor

Abstract

According to the closed type hydraulic oil cylinder system driven by the motor, in the action process of the oil cylinder, the oil sucking and discharging amount of the hydraulic pump / motor is equal, additional hydraulic oil supplementing is not needed, the motor can output torque or control the rotating speed, the hydraulic pump / motor is driven, and the oil cylinder executes actions according to the needed direction and speed. The closed hydraulic oil cylinder system comprises an oil cylinder a and an oil cylinder b, and the oil cylinder a and the oil cylinder b are both double-acting piston type oil cylinders with rod cavities and rodless cavities. When the moving distance of the piston rod of the oil cylinder a is equal to that of the piston rod of the oil cylinder b, the displacement difference of the oil cylinder a is equal to that of the oil cylinder b, a rod cavity of the oil cylinder a is communicated with a rodless cavity of the oil cylinder b and is communicated with a first liquid inlet / outlet of the hydraulic pump / motor, and the rodless cavity of the oil cylinder a is communicated with a rod cavity of the oil cylinder b and is communicated with a second liquid inlet / outlet of the hydraulic pump / motor. The first liquid inlet / outlet is communicated with a second liquid inlet / outlet of the hydraulic pump / motor; the motor drives the hydraulic pump / motor; the controller controls the motor output torque and the motor rotating speed.

Description

Technical Field

[0001] This utility model relates to a closed hydraulic system, specifically a motor-driven closed hydraulic cylinder system. Background Technology

[0002] In the field of construction machinery, open hydraulic structures are generally used. Due to the use of a single engine, the hydraulic system design is very complex. The high-speed flow of hydraulic oil in the oil circuit results in a complex system structure and low efficiency.

[0003] Closed-loop hydraulic transmission can largely avoid ineffective hydraulic oil flow and has high transmission efficiency. However, closed-loop hydraulic systems are mainly suitable for scenarios where the loads in two directions are relatively balanced and the oil intake and discharge volumes of the actuators are equal during forward and reverse movements, such as the swing and travel of excavators. For cylinder-type actuators, due to unbalanced loads and large differences in oil intake and discharge volumes, it is difficult to implement closed-loop hydraulic systems. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of high energy consumption and safety caused by unbalanced loads, and to realize the application of hydraulic cylinders as actuators in closed hydraulic systems. It provides a motor-driven closed hydraulic cylinder system in which the hydraulic pump / motor draws in and discharges oil at the same rate during the operation of cylinders a and b, eliminating the need for additional hydraulic oil replenishment and meeting the operating standards of closed hydraulic systems. Furthermore, the motor can output torque or control the speed to drive the hydraulic pump / motor, enabling cylinders a and b to perform actions in the required direction and speed.

[0005] A motor-driven closed-loop hydraulic cylinder system includes cylinder a and cylinder b, both of which are double-acting piston cylinders with rod chambers and rodless chambers. When the piston rods of cylinder a and cylinder b travel the same distance, the displacement difference between cylinder a and cylinder b is equal, meaning the difference in hydraulic oil volume entering and exiting the rod chamber and rodless chamber of cylinder a is equal to the difference in hydraulic oil volume entering and exiting the rod chamber and rodless chamber of cylinder b. The rod chamber of cylinder a is connected to the rodless chamber of cylinder b and is connected to the first inlet / outlet of a hydraulic pump / motor via a first oil circuit. The rodless chamber of cylinder a is connected to the rod chamber of cylinder b and is connected to the second inlet / outlet of the hydraulic pump / motor via a second oil circuit. The motor is directly or indirectly connected to the hydraulic pump / motor to drive it. A controller is electrically connected to the motor to control the output torque and speed of the motor.

[0006] The aforementioned closed hydraulic cylinder system also includes a brake that brakes the motor. The controller is electrically connected to the motor and the brake to control the movement of the motor and the brake.

[0007] In the aforementioned closed-loop hydraulic cylinder system, the first oil circuit is equipped with a first solenoid valve, and the controller is electrically connected to the motor and the first solenoid valve to control the operation of the motor and the first solenoid valve.

[0008] In the aforementioned closed-loop hydraulic cylinder system, a second solenoid valve is installed in the second oil circuit. The controller is electrically connected to the motor and the second solenoid valve to control the operation of the motor and the second solenoid valve.

[0009] In the aforementioned closed-loop hydraulic cylinder system, a replenishment branch is provided between the first or second oil circuit and the oil tank for replenishing hydraulic oil to the first or second oil circuit; the replenishment branch has a replenishment check valve that allows hydraulic oil to flow from the oil tank into the first or second oil circuit.

[0010] In the aforementioned closed-loop hydraulic cylinder system, an overflow branch with an overflow valve is provided between the first or second oil circuit and the oil tank.

[0011] In the aforementioned closed hydraulic cylinder system, a pressure sensor is installed in either the first or second oil circuit, and the pressure sensor is electrically connected to the controller.

[0012] In the aforementioned closed-loop hydraulic cylinder system, the piston rod of cylinder a and the cylinder barrel of cylinder b are directly connected or fixedly connected through a first intermediate component, and the cylinder barrel of cylinder a and the piston rod of cylinder b are directly connected or fixedly connected through a second intermediate component. This results in a more compact overall structure.

[0013] This utility model also provides a control method for a motor-driven closed hydraulic cylinder system. Using this system, when both cylinders are operating normally, the controller controls the motor's speed and output torque to drive the hydraulic pump / motor, causing the cylinder's piston rod to extend and retract. When the cylinder stops moving or ceases operation, the motor stops moving and output power, achieving energy saving. When the cylinder's piston rod moves under load, the hydraulic oil drives the pump / motor to reverse the motor and generate electricity, which is then stored and reused.

[0014] The control method for the above-mentioned motor-driven closed hydraulic cylinder system, when the cylinder stops moving or stops working, controls the motor to stop moving and the motor to stop outputting power. At the same time, the motor is braked, or the first solenoid valve on the first oil circuit is shut off, or the second solenoid valve on the second oil circuit is shut off, thereby achieving energy saving.

[0015] The beneficial effects of this utility model are:

[0016] Since the piston rods of cylinders a and b travel the same distance, the displacement difference between cylinder a and cylinder b is equal. This means the difference in hydraulic oil flow between the rod-side and rodless-side chambers of cylinder a is equal to the difference in hydraulic oil flow between the rod-side and rodless-side chambers of cylinder b. Therefore, when cylinders a and b are working, the amount of hydraulic oil flowing through the first oil circuit is equal to the amount flowing through the second oil circuit, and the suction and discharge volumes of the hydraulic pump / motor are equal. No additional hydraulic oil needs to be added, truly achieving a closed-loop hydraulic system.

[0017] The motor is connected to the hydraulic pump / motor to drive the hydraulic pump / motor; the controller is electrically connected to the motor to control the output torque and speed of the motor.

[0018] When cylinders a and b are working normally, the load is entirely borne by the motor. The motor, based on the output torque or control speed, causes the cylinders to perform actions in the required direction and speed.

[0019] When the hydraulic cylinder stops moving or ceases operation, the motor also stops, thus achieving energy savings. To prevent the hydraulic cylinder from moving under external force (load), the motor can be braked, or the first solenoid valve on the first hydraulic circuit can be shut off, or the second solenoid valve on the second hydraulic circuit can be shut off.

[0020] Of course, when the piston rod of the hydraulic cylinder moves under the load, the hydraulic oil drives the pump / motor to drive the motor to reverse and generate electricity. The electrical energy generated by the motor in reverse can also be stored and reused to achieve energy recovery, which can greatly save the energy consumption of construction machinery and has high application value. Attached Figure Description

[0021] Figure 1 , 2 1, 2, 3, 4, and 5 are schematic diagrams of the closed hydraulic cylinder systems in Examples 1, 2, 3, 4, and 5, respectively. Detailed Implementation Example 1

[0022] See Figure 1The motor-driven closed hydraulic cylinder system shown includes cylinder a1 and cylinder b2. Both cylinder a and cylinder b are double-acting piston cylinders with rod chambers and rodless chambers. When the piston rods of cylinder a and cylinder b travel the same distance, the displacement difference of cylinder a is equal to the displacement difference of cylinder b. That is, the difference in the amount of hydraulic oil entering and exiting the rod chamber and rodless chamber of cylinder a is equal to the difference in the amount of hydraulic oil entering and exiting the rod chamber and rodless chamber of cylinder b. The rod chamber of cylinder a1 is connected to the rodless chamber of cylinder b2, and is connected to the first inlet / outlet of hydraulic pump / motor 5 through the first oil passage 3. The rodless chamber of cylinder a is connected to the rod chamber of cylinder b, and is connected to the second inlet / outlet of hydraulic pump / motor 5 through the second oil passage 4. Motor 6 is directly or indirectly connected to hydraulic pump / motor 5 to drive hydraulic pump / motor. Controller (control computer) 7 is electrically connected to motor 6 to control the output torque and speed of motor.

[0023] When the two cylinders (cylinder a and cylinder b) are in normal working condition, the controller controls the speed and output torque of the motor to drive the hydraulic pump / motor, causing the piston rod of the cylinder to extend and retract. When the cylinder stops moving or stops working, the motor stops moving and stops outputting power, thus achieving energy saving. When the piston rod of the cylinder moves under load, the hydraulic oil drives the pump / motor to drive the motor to reverse and generate electricity, which is then stored and reused. Example 2

[0024] See Figure 2 The difference between Embodiment 2 and Embodiment 1 is mainly that: a replenishment branch for replenishing hydraulic oil to the first and second oil circuits is provided between the first oil circuit and the oil tank; a replenishment check valve 8 is provided on the replenishment branch to allow hydraulic oil to flow from the oil tank to the first and second oil circuits; an overflow branch with an overflow valve 9 is provided between the first and second oil circuits and the oil tank; a pressure sensor 10 is provided on the first and second oil circuits, and the pressure sensor 10 is electrically connected to the controller 7; a brake 11 is provided to brake the motor, and the controller is electrically connected to the brake 11 to control the action of the brake.

[0025] When the hydraulic cylinder stops moving or stops working, the controller stops the motor and simultaneously controls the brake to apply pressure to the motor. At this time, due to the rotation of the brake, the piston rod of the hydraulic cylinder cannot move under the load, and the hydraulic oil will not drive the pump / motor to reverse the motor. Example 3

[0026] See Example 3 Figure 3 The main difference between this embodiment and embodiment 2 is that the first oil circuit 3 is equipped with a first solenoid valve 12, and the controller is electrically connected to the first solenoid valve 12 to control the action of the first solenoid valve; the brake in embodiment 3 is not present in embodiment 2.

[0027] When the hydraulic cylinder stops moving or ceases operation, the controller stops the motor and simultaneously shuts off the first solenoid valve. At this time, the piston rod of the hydraulic cylinder cannot move under load, and the hydraulic oil will not drive the pump / motor to reverse the motor. Example 4

[0028] See Figure 4 The difference between Embodiment 4 and Embodiment 3 is mainly that: the second oil circuit 5 is provided with a second solenoid valve, the controller 7 is electrically connected to the second solenoid valve, and both ends of the second solenoid valve and the first solenoid valve are connected in parallel with check valves 13, and the two check valves 13 allow the hydraulic oil to flow in opposite directions.

[0029] When the hydraulic cylinder stops moving or ceases operation, the controller stops the motor and simultaneously shuts off both the first and second solenoid valves. At this time, the piston rod of the hydraulic cylinder cannot move under load, and the hydraulic oil will not drive the pump / motor to reverse the motor. Example 5

[0030] See Figure 5 The difference between Embodiment 5 and Embodiment 1 is mainly that the piston rod of cylinder a1 and the cylinder barrel of cylinder b2 are fixedly connected by a first intermediate member 15, and the cylinder barrel of cylinder a1 and the piston rod of cylinder b are fixedly connected by a second intermediate member 16. Both the first intermediate member 15 and the second intermediate member 16 have lugs for hinged connection with external structures.

[0031] A motor-driven closed-loop hydraulic cylinder system includes at least one motor, one hydraulic pump / motor (such as a piston pump / motor), one oil pressure sensor, and two oppositely mounted cylinders (cylinder a and cylinder b). The displacement difference between the two oil chambers of the two cylinders is equal when the piston rods move the same distance. The different oil chambers of the two cylinders are connected. At least one solenoid valve is connected in series between the hydraulic pump / motor and the cylinder circuit to lock the cylinder to reduce energy consumption. Alternatively, a brake can be installed on or at any point connected to the motor shaft to lock the cylinder and reduce energy consumption. A control computer is used to perform signal processing and control the motor, brake, or solenoid valve.

[0032] As an auxiliary component, a replenishing valve and a relief valve are installed in the hydraulic circuit, which is a standard configuration.

[0033] As an auxiliary measure, a check valve can be connected in parallel across the solenoid valve to prevent negative pressure from adversely affecting the sensor, hydraulic system, etc.

[0034] A check valve and a solenoid valve can be installed at each end of the hydraulic pump / motor.

[0035] The hydraulic pump / motor is preferably a pump / motor that can be used as both a piston pump and a motor, but other types of hydraulic pump / motors that can be used as both pumps and motors are also acceptable.

[0036] The solenoid valve can be a bidirectional shut-off / open control solenoid valve or a unidirectional shut-off / open control solenoid valve.

[0037] The solenoid valve can be a direct-acting solenoid valve or a pilot-operated solenoid valve.

[0038] Increasing the number of pressure sensors appropriately can improve control performance and reliability, but does not affect the scope of protection of the claims of this utility model.

[0039] The cylinders, hydraulic pumps / motors, valves, etc. mentioned are only used to describe the system structure, and their specific structures do not affect the scope of protection of the claims of this utility model.

[0040] Solenoid valves can be placed on either side of the hydraulic pump / motor, or on both sides simultaneously.

[0041] The various valves mentioned can be independent or combined, or a single valve can have multiple functions. For example, a solenoid valve and a check valve connected in parallel on both sides of the solenoid valve can be replaced by a single check solenoid valve.

[0042] The aforementioned control computer (controller) refers to a unit or a combination of multiple control units capable of processing input signals and output control.

[0043] When the hydraulic cylinder needs to move, the control computer, based on the cylinder's oil chamber pressure feedback from the pressure sensor, instructs the motor to output the corresponding torque. This prevents the cylinder from moving under load and producing actions contrary to the intended control after the solenoid valve opens (or the brake is released). Afterward, the solenoid valve activates the oil circuit, at which point the load is entirely borne by the motor. The motor outputs torque or controls the speed according to the controller's instructions, causing the cylinder to perform actions in the required direction and speed. When the cylinder stops moving or ceases operation, the control computer instructs the solenoid valve to close or the brake to engage, after which the motor stops outputting power, achieving energy savings. Furthermore, because the motor can reverse to generate electricity under load, achieving energy recovery, it can significantly reduce the energy consumption of construction machinery, making it highly valuable.

[0044] Two oppositely mounted hydraulic cylinders (two opposing hydraulic cylinders): Since the displacement of the two chambers of the two hydraulic cylinders is complementary, the pump's suction and discharge volume is equal during the operation of the hydraulic cylinders, which meets the standard for the operation of a closed hydraulic system.

Claims

1. A motor-driven closed-loop hydraulic cylinder system, comprising cylinder a and cylinder b, both cylinder a and cylinder b being double-acting piston cylinders having rod-side and rodless sides; characterized in that: When the piston rods of cylinders a and b travel the same distance, the displacement difference between cylinders a and b is equal, meaning the difference in hydraulic oil volume between the rod-side and rodless-side chambers of cylinder a is equal to the difference in hydraulic oil volume between the rod-side and rodless-side chambers of cylinder b. The rod-side chamber of cylinder a is connected to the rodless-side chamber of cylinder b and is connected to the first inlet / outlet of the hydraulic pump / motor via a first oil circuit. The rodless-side chamber of cylinder a is connected to the rod-side chamber of cylinder b and is connected to the second inlet / outlet of the hydraulic pump / motor via a second oil circuit. The motor is directly or indirectly connected to the hydraulic pump / motor to drive it. The controller is electrically connected to the motor to control the output torque and speed of the motor.

2. The closed-loop hydraulic cylinder system as described in claim 1, characterized in that: It also includes a brake that brakes the motor. The controller is electrically connected to the motor and the brake to control the movement of the motor and the brake.

3. The closed-loop hydraulic cylinder system as described in claim 1, characterized in that: The first oil circuit is equipped with a first solenoid valve. The controller is electrically connected to the motor and the first solenoid valve to control the operation of the motor and the first solenoid valve.

4. The closed-loop hydraulic cylinder system as described in claim 1, characterized in that: The second oil circuit is equipped with a second solenoid valve. The controller is electrically connected to the motor and the second solenoid valve to control the operation of the motor and the second solenoid valve.

5. The closed hydraulic cylinder system as described in any one of claims 1-4, characterized in that: A replenishment branch is provided between the first or second oil circuit and the oil tank for replenishing hydraulic oil to the first or second oil circuit; the replenishment branch has a replenishment check valve that allows hydraulic oil to flow from the oil tank into the first or second oil circuit.

6. The closed hydraulic cylinder system as described in any one of claims 1-4, characterized in that: An overflow branch with an overflow valve is provided between the first or second oil line and the oil tank.

7. The closed hydraulic cylinder system as described in any one of claims 1-4, characterized in that: A pressure sensor is installed in either the first or second oil circuit, and the pressure sensor is electrically connected to the controller.

8. The closed hydraulic cylinder system as described in any one of claims 1-4, characterized in that: The piston rod of cylinder a is directly connected to the cylinder barrel of cylinder b or is fixedly connected through a first intermediate component. The cylinder barrel of cylinder a is directly connected to the piston rod of cylinder b or is fixedly connected through a second intermediate component.

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